Waveform Analysis of the Doppler Curve of Ophthalmic Arteries in Glaucoma Patients

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Color Doppler Imaging (CDI) has been providing information about ocular blood flow over the past decades. This non-invasive procedure based on ultrasound technique has identified increased resistance and decreased systolic blood velocities to exist in the ophthalmic arteries of glaucoma patients. However, existing data has provided very little information regarding the analysis of the Doppler waveform in itself and to whether variables such as early systolic acceleration or systolic/diastolic velocity ratios are of any significance in glaucoma disease. In other medical specialties using CDI technology, such as nephrology or cardiology for instance, this analysis has been part of the normal routine. This information has been used in screening patients for disturbed circulation such as arterial stenosis or providing information regarding prognosis of renal and hepatic transplants have been used for decades now.

What is the normal characteristics of the waveform Doppler analysis? To answer this, the investigators will create a normative database using healthy controls.

Are there signs of altered stiffness or compliance in the ophthalmic arteries of glaucoma patients? To answer this, the analysis of early acceleration acceleration and detection of an early peak systolic will be done on the Doppler curves of glaucoma patients and compared to the healthy normative database.

Are there any difference between the two types of glaucoma [primary open-angle glaucoma (POAG) and normal-tension glaucoma (NTG)]? The investigators will compare the variables of the ophthalmic artery waveform in these two groups.

Do any of these Doppler waveform variables have any clinical significance? To answer this, the investigators will search for the existence of any correlation between the waveform data and both functional (visual field testing) and structural (Confocal scanning laser ophthalmoscopy - CSLO) variables of the glaucoma groups.

Condition or disease

Open-angle GlaucomaLow Tension Glaucoma

Detailed Description:

1. Color Doppler imaging of the ophthalmic artery will be performed 2. Visual field testing will be done 2. CSLO will be done

Early Systolic Acceleration as a measure of vascular disfunction of the ophthalmic arteries in glaucoma patients [ Time Frame: hospital stay, average 3 hours ]

Color Doppler Imaging of the ophthalmic artery will provide the waveform of the vessel. There will be a operator-dependent identification of the slope at the beggining of the cardiac cycle and a quantification of the early systolic acceleration. This numberical data will then be compared between healthy and glaucoma groups. Such variables will further be compared to the clinical data (functional - visual field defects and structural - CSLO).

Secondary Outcome Measures :

Ratio between systolic and diastolic blood flow velocities as a measure of arterial compliance of the ophthalmic artery in glaucoma patients [ Time Frame: Hospital stay, average 3 hours ]

Using the CDI-provided ophthalmic artery waveform, there will be an operator-dependent analysis of systolic and diastolic mean blood flow velocities. the ratio between these two variables will be calculated and the numerical data obtained will be compared between the healthy and glaucoma groups. Such ratio will furthermore be compared to functional and structural damage (visual field damage and CSLO, respectively).

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Ages Eligible for Study:

18 Years and older (Adult, Senior)

Sexes Eligible for Study:

All

Accepts Healthy Volunteers:

Yes

Sampling Method:

Probability Sample

Study Population

primary care clinic

Criteria

Inclusion Criteria:

• individuals over 18 years old

willing to sign an informed consent and able to comply with the requirements of the study